In most people, low-level sweat production is a constant process, and much of that sweat doesn't even come out of the sweat glands; it's simply reabsorbed by the body. High-level sweat production is another matter. The process can kick off from exercise, high temperatures or stimulation from nerves in response to an emotion, like anxiety or fear. To learn more about how the body's sweat glands function, read How Sweat Works.
The nerves that react to stress get their cues through the sympathetic nervous system, which in turn is part of the autonomic nervous system. The sympathetic nervous system is responsible for preparing the body to respond to dangerous or stressful situations. When something of this nature occurs, the sympathetic system readies the body in a number of ways -- including increasing sweat production. It does this by stimulating the sweat glands with a chemical neurotransmitter called acetylcholine. This chemical rests in tiny sacs located between the nerves and sweat glands until it is needed. When released, this chemical forces the sweat glands into action, and the glands will continue to react until the acetylcholine has been depleted. (If the perceived threat hasn't passed at that point, more acetylcholine is released for the reaction to continue.)
For people with hyperhidrosis, the nerves that serve the sweat glands in certain portions of the body will go into overdrive from time to time and produce sweat for no reason at all. The frequency, duration and strength vary by person. There is no conclusive evidence as to why the nerves do this, but they will bombard sweat glands with unnecessary acetylcholine, causing a very sticky situation for some people.
So what is it like to have hyperhidrosis? Do you just slather on some extra deodorant as you head out the door? Go to the next page to find out what life with hyperhidrosis is like.